Traumatic brain injury leaves 17,000 children disabled yearly. Many children do not achieve their expected developmental trajectory after injury. Services exist for children with specific developmental disorders when they are known to be at risk for delays; however, children with traumatic brain injury frequently do not access these services. The overall goal of this project is to understand how traumatic brain injury affects children's development. This project is a longitudinal, prospective cohort study of children 0 to 15 years of age with all severities of traumatic brain injury. Children with traumatic brain injury and a comparison group of age and sex- matched children with orthopedic injury will be recruited from the two participating institutions. Specifically, the aims of this project are to fist characterize this cohort of children and age and sex matched orthopedic injury comparison children in relation to acute, post-acute and longer term treatments. We will characterize the children's family environment and cognitive and socio-emotional reserve as these may influence changes in children's short and longer term health status. Then, we will measure health specific outcomes during the first year after injury, including physical health, post-concussion symptoms, and stress. We will assess children's longer term developmental progress using growth curve analysis of key neuropsychological domains including cognition, social, and psychological health outcomes compared to children with orthopedic injuries. We will then use structural equation modeling to examine the relationships of injury severity, family environment, and neuropsychological status on children's ability to participate in everyday activities and perform i school. Finally, we will quantify children's health service use and health care costs for the year following injury. Results of this research will help to understand the complex interactions of preinjury family and child characteristics, post injury child deficits and family stress on childre's developmental outcomes. This information will be integrated with the children's current health service and school support service use in order to understand the barriers to services and inform the needed supports for children at each developmental stage.